1. Field of the Invention
This invention relates to the control of plant pathogens. More particularly, this invention relates to the control of fungal foliar phytopathogens, especially downy mildew and late blight, using a broad class of 2,6-dinitroanilines.
2. Description of the Prior Art
Beginning in the early 1960's, Soper disclosed that 2,6-dinitroanilines possess herbicidal activity, most notably preemergent herbicidal activity. See, for example, U.S. Pat. Nos. 3,111,403; 3,257,190; 3,332,769; and 3,367,949. Following Soper's lead, a large number of related dinitroanilines have also been shown to possess similar herbicidal activity. See, for example, U.S. Pat. Nos. 3,321,292; 3,617,251; 3,617,252; 3,672,864; 3,672,866; 3,764,624; and 3,877,924 and Belgian Pat. No. 787,939. See also U.S. Pat. No. 3,725,479, for intermediate compounds.
Malichenko et al., Fiziol. Aktiv. Veschestva 1969, 2, 75-8; C.A. 73, 13451e (1970), disclose that some 2,6-dinitroanilines bearing a trifluoromethyl group in the 4-position possess some activity against Phytophthora infestans, the causative organism of late blight of tomatoes.
Clark et al., U.S. Pat. No. 3,119,736, disclose a broad class of compounds alleged to be fungicides. The generic description of such compounds includes dinitroanilines, but there is no specific disclosure of 2,6-dinitroanilines.
Zsolnai, Biochemical Pharmacology, 5, 287-304 (1961), discloses that certain 2,4-dinitroanilines possess some fungicidal activity against various organisms. No 2,6-dinitroaniline was disclosed, nor was Plasmopara viticola among the organisms against which activity was shown.
Buczacki, Ann. Appl. Biol. 75, 25 (1973), tested five dinitroanilines against clubroot of cabbage with variable results. He concluded, however, that "dinitroanilines are unlikely to be of value in the control of clubroot."
Eshel and Katan, Weed Science 20, 243 (1972), observed the effects of four dinitroanilines against Rhizoctonia solani and Fusarium oxysporum. Three of the four test compounds decreased the growth of R. solani at the highest rates tested, but none of the four appreciably decreased the growth of F. oxysporum at any rate tested.
A study of trifluralin-treated soil by Breazeale and Camper, Appl. Microbiol. 19, 379 (1970), indicated that the actinomycete population increased as compared to the control, while the population of bacteria and fungi decreased.
A discussion of tests against the fungus Lagenidium callinectes is presented by Bland et al. in a paper entitled "Chemical Control of Lagenidium", an SEA Grant Publication UNC-SG-76-02, March 1976. The publication shows that some control of the fungus, which is a parasite of marine crustacea, is accomplished by application of TREFLAN (trifluralin) to water in which spores of the fungus were growing.